This invention relates to an ELEVATOR WHICH COUNTERWEIGHT IS ALSO THE PLUNGER OF THE PROPELLING FLUID DYNAMIC DEVICE WHICH PRODUCES AND CONTROLS THE MOVEMENTS THEREOF, that brings several advantages over the other vertical translation devices known so far.
More specifically, this invention relates to an elevator lifter for vertically carrying people or things, of the type having a car which moves between vertical guides, arranged within a conduit called xe2x80x9choistwayxe2x80x9d, said car being supported on a cable extending to a pulley or wheel that is part of the elevator, wherefrom it projects for extending to a counterweight means which is cooperative with said elevator.
In very well known embodiments, said pulley is powered by an electrical engine which operates the cable extending between the car and the counterweight.
The usual, universally known purpose of the xe2x80x9ccounterweightxe2x80x9d is to reduce the power of the engine. In fact, generally the counterweight has a weight that is equal to that of the car increased in about 40 to 45% of the duty load; in this way the engine only has to lift the unbalanced part of the load and avoid any rubbing.
In this particular case, the invention relates to an elevator conceived with the novel feature of using the counterweight as a piston or plunger of a fluid dynamic device that propels said vertical movements to the car.
For the rest of the constructive aspects, the inventive elevator, as regards its car and assembly (guides, parachutes, and the like), is of a conventional type. It is a rule-conforming, xe2x80x9cstandardxe2x80x9d elevator.
Consequently, this is an embodiment that from the beginning avoids the need of installing a lifting machine that may be arranged either above or below the hoistway for commanding the movement of said wheel that drives and powers the cable. Instead, a single freely rotating pulley is disposed, the function of which is to guide the cable to the equilibrated counterweight which, as indicated by the title of the invention, is the plunger of the propelling fluid dynamic device.
Several constructive and functional embodiments of elevators are known. Among these embodiments, the most traditional one is that in which cables guided and powered from a generally electrical engine are used for the vertical movement of the car. There also exist some others that usually use vertical racks wherein the operating teeth are engaged, the teeth being powered by an engine accommodated in the car itself.
Among the elevators that use propelling fluid dynamic devices are both, hydraulic lifts and pneumatic lifts. Hydraulic lifts known at present have similar features located to that of electrical lifts. The car also moves being guided by vertical steel profiles placed in the hoistway and have the characteristic of including a cylinder inside which a piston for raising the car moves. A tight pipe extends from the cylinder bottom to the liquid reservoir; the liquid reservoir is generally placed in the machine room, where also the hydraulic pump is accommodated with its corresponding engine and directional valves. The pump pressure injects liquid in the bottom of the cylinder, so the plunger is pushed upwards, thus raising the car. When the fluid supply is interrupted, the car stops. Downward movement starts from an electrical order, which produces the opening of the valves so as to allow for the liquid to go back to the reservoir. The weight of the plunger, the car, the load and the fluid itself, generate a pressure sufficient for the liquid to outflow. As fluid pressure varies according to the load being carried, downward movement speed also varies as a function of the load.
The advantage of this type of lifters is that no large installations above the hoistway are required, so it is fully used for movements of the car.
A generalized drawback is that the length of the cylinder should be slightly longer that the car path of motion, which creates the need for large installations out of the hoistway, generally below the hoistway. It is for this reason that they have a limited distance to travel (two or three stops). They are devices that operate under great pressure, so their installations are highly expensive, not only due to their size, but also for the constructive precision of the hydraulic parts necessary for them.
In this sense, those, which use side pistons, are preferred, as their stroke is half the path of motion of the car; nevertheless the pulley systems that are used led to duplication of efforts with a lot of rubbing.
In fact, the hydraulic elevators known at present, the cylinders and pistons are rectified and require good seals or detents to support pressures higher than 5 kg/cm2, i.e. 5 atmospheres or higher.
Among disclosures prior to this application U.S. Pat. No. 3,318,418 to William C. Kilpatrick can be mentioned, wherein it is taught an installation for a pneumatic elevator of the type where the car vertically moves as a piston within a tube (that forms the hoistway of the lift), in response to the pneumatic pressure existing in said tube, below the car.
U.S. Pat. No. 2,927,661 to Kristek et. al. teaches a lifter for people or loads that also uses a tight closing tube wherein a car moves. Said tube is part of a very particular pneumatic circuit where air is pressure-flown so as to produce the raising of the car. French patent number 71.02437 to Saunier Duval discloses a car which is the piston of a vertical pneumatic cylinder that moves upwards, by effect of an overpressure applied below the car, while it moves downward when a depressurization inside the tube and over the car is caused.
The applicant of the present invention is also the creator of a depressurization pneumatic elevator which was the subject matter of the Argentinean patent 245673 which fits a special construction through which the car raises or moves downward as a function of the depressurizations created between the ceiling of the car and the upper part of the tube over which it moves.
There are no previous disclosures regarding the use of the counterweight itself as a propelling means for moving the car upward and downward. In all cases they are used with the purpose of balancing the load, in an attempt that the effort made by the propelling means be the lowest possible. In this regard, mention is made to EP 0 957 060 to Klitzke Dieter where a conventional hydraulic elevator having the counterweight disposed external to the propelling cylinder is disclosed.
U.S. Pat. No. 5,901,814 to Leandre Adifon et. al. teaches an hydraulic elevator having a counterweight. In this case, the car is associated to the piston of a hydraulic cylinder, which is the propelling means for upward and downward movements thereof. In this case, the counterweight acts as such. It has the function of reducing the effort of the cylinder for movements. It has the same function as the balanced counterweights used in most elevators.
U.S. Pat. No. 5,957,779 to Walter F. Larson refers to a tower with a couple of gondolas hanging therefrom which, by their free ends, are attached to the piston of a hydraulic cylinder. Single counterweights are included for each gondola hanging from the same piston as a resource for balancing the load. Counterweights are not used as a propelling resource, either.
U.S. Pat. No. 5,975,246 to Renzo Toschi teaches a hydraulically balanced elevator. The patent discloses an elevator combining the use of a first cylinder and a second cylinder which are integral with a single hydraulic circuit which regulates the balance of the load in the car. Counterweights are included on the second cylinder. Neither in this case counterweights are used as movement propelling.
U.S. Pat. No. 5,238,087 to Alfonso Garrido et. al. relates to improvements tending to achieve energy savings for hydraulic elevators. In this case an hydraulic means is disclosed, the means is attached to the counterweight means so as to bear the weight of the car plus a 50$ of the duty load. It is a counterweight associated to a hydraulic resource, but nonetheless the use of the counterweight as a propelling means is not disclosed.
There exist, in fact, damping resources for downward movement, where the counterweight is integral with specific hydraulic circuits.
U.S. Pat. No. 4,488,621 to Herbert L. Schiewe relates to an emergency elevator. It is a cage coupled to a damping cylinder, which is integral with a valve-controlled circuit. No propelling counterweights are taught. The cylinder is disposed laterally to the cage and the damping piston has a weight slightly higher than the cage, even when it is used for raising the cage when it is empty (free from load).
It is a device specially designed for bringing people downwards in case of emergency, where downward movement of the cage is restrained by the piston.
There are no previous disclosures regarding the use of the counterweight itself as a propelling means.
In fact, elevators of the conventional type, which are powered by electric engines, the balanced counterweight alleviates the effort required by the engine for the upward and downward movement of the car.
For fluid dynamic elevators (both, hydraulic and pneumatic), constructions where the car is the operating means, either as a piston of the actuator or associated to a plunger or piston that supports and translates said car are used.
In no case, disclosures exist in that the counterweight is used as the piston of a propelling fluid dynamic device. This operating principle brings several advantages, not only constructive, but also related to installation and maintenance, since similar or even better results are achieved with lower effort.
From the operating principle above stated, it is possible to construct hydraulic and pneumatic installations that makes the plunger to move, which are dimensioned related to the counterweight that they move, so they turn out to be simpler and cheaper than fluid dynamic installations known so for actuating the car.
From the above operating principle, it is much simpler the assembly of the car inside the hoistway where it moves, as the presence of the machine associated to the electric engine is avoided, which is usually disposed in the upper part. In this case, it is replaced by a single pulley where the cable is deviated to the counterweight, the function of which will be only to allow for the change of direction in the vertical movements for raising and moving downward.
Note that for the case of the elevator of this invention, it is not necessary for the traditional machine room to be built in the upper part of the hoistway, so it can be fully used for the car movements.
Comparing this invention to the prior hydraulic elevators above, the invention results to be advantageous as regards installation since it is not necessary to place cylinders below the hoistway of the elevator or in a position lateral to the hoistway which require special installations with multiple pulleys.
Likewise, when comparing this embodiment to other pneumatic elevators, where the car is usually used as part of the fluid dynamic installation which causes the propulsion thereof, mention is made to the fact that in this case it is not necessary to have special conduits or pipes for the car movement, since neither tightness nor insulation in the interior of the car is required.
It is specially noted that, under the foregoing operation principle, for achieving the same or even better results, no specially dimensioned means are required, it is not necessary to submit the means to any special treatment (rectification, etc), and no special, expensive materials are used.
In fact, to achieve movement of counterweights by means of a pneumatic or hydraulic installation it is possible to use conventional cylinders (which do not need to be oversized), for pressures to which they are submitted are not high. So, it is unnecessary to perform special rectification works in the rubbing surfaces so as to correct fabrication defects, since the seals may easily absorb them. In the preferred embodiments pressures lower than atmospheric pressure shall be used.
In the preferred embodiments, the cylinders shall be placed within the hoist itself, where the car displaces, since its plan area may be up to ten times smaller than the plan surface of the car, while the length of the height shall be equivalent to the length of the path of motion of the car added to the stroke of the piston-counterweight.
The inventive elevator may use a counterweight-piston which weight is slightly lighter than the weight of the car, is the same as the weight of the car, or is heavier than the weight of the car. Should the weight be lighter than the weight of the car, power shall be consumed only for raising the elevator, as downward movement shall be regulated by means of valves, which are also of the conventional type and known per se.
After the explanation above, it can be seen that the main object of the invention is an ELEVATOR WHICH COUNTERWEIGHT IS ALSO THE PLUNGER OF THE PROPELLING FLUID DYNAMIC DEVICE WHICH PRODUCES AND CONTROLS THE MOVEMENTS THEREOF, of the type comprising a car for conveying people or things which moves between vertical guides disposed in a vertical conduit called hoistway, which is supported by a cable extending to an upper pulley and, changing the direction, extends to a counterweight balanced with said car; one of the main characteristics of the assembly is that said pulley is supported from the hoistway walls and is kept in a freely-rotating condition, while the balanced counterweight is a hollow piston-counterweight, located in a cylinder vertically disposed in the hoistway itself, adjacent to the car, both being integral with a propelling fluid dynamic device which produces upward and downward movements of the car, which is completed with a fluid circulation circuit, which comprises at least a driving pump coupled to valve means.
The invention provides for the cylinder to have a length slightly longer than the vertical path of motion that the car has to travel between the lower and the upper stops. The invention provides for the propelling device to be pneumatic, which driving pump is a rotary compressor coupled to solenoid valves.
The propelling device may be also hydraulic, which driving pump is a volumetric hydraulic pump, or a centrifugal pump, coupled to solenoid valves.
It is an option of the construction of this invention that the vertically disposed cylinder have the upper and lower bases thereof closed, and defining inside thereof two variable volume chambers, spaced apart by the piston-counterweight, both chambers are individually connected to a respective conduit for the fluid flow, extending to the driving pump of the propelling device.
It is also provided a vertically disposed cylinder, having an open upper basis and defining a variable volume chamber delimited by the piston-counterweight, while the lower basis is closed; the chamber is connected by conduits for inflow and outflow of the fluid, extending to the driving pump coupled to the valve means of the propelling device and the fluid reservoir or tank.
Also, it can be clearly seen that the fluid flow may be a pneumatic circuit comprising at least a pneumatic pump coupled to valve means, including air intake devices matching the variable volume chambers.
It is also provided that the fluid flow circuit be a hydraulic circuit, comprising at least a hydraulic pump coupled to valve means interbedded in fluid flow conduits which are connected to said chambers.
For the case of a pneumatic circuit, the fluid flow circuit, comprising at least a driving pump coupled to valve means, is external to the cylinder body accommodating the piston-counterweight and connects with it through conduits.
The invention also features a fluid flow circuit, comprising at least a driving pump coupled to valve means, which may be a closed circuit disposed inside the cylinder accommodating the piston-counterweight.
It is also provided that the driving pump and associated valve means may be directly disposed inside the piston-counterweight, being integral with the conduits that communicate with the variable volume chambers that may be specified with said piston-counterweight and the cylinder walls, defining a closed circuit.
The invention also provides for the driving pump and associated valve means to be accommodated inside the piston-counterweight, being integral with the conduits connecting the variable volume chambers specified with said piston-counterweight and the cylinder walls, including the respective valves for atmosphere air intake matching each chamber.
On the other side, the invention provides for the piston-counterweight to be hollow and accommodating inside thereof removable ballast elements.
The cable extending between the car and the piston-counterweight may be a sheathed cable.
Finally it is also pointed out that pivotable anchor bolts are included as matching the ceiling of the car, said anchor bolts oscillate about a transversal axis, which free ends face their respective anchoring cavities, defined in the hoistway walls matching each stop level, which transversal movements (for locking and unlocking actions) are commanded from an electromechanical means being integral with the operating circuit of the elevator; while the oscillatory movements thereof produced during loading and unloading of the car actuate electronic sensors integral with the operating circuit of the propelling device (with the purpose of ordering the automatic balancing of the piston-counterweight).